A large number of perfumes are known and are widely used in consumer products (referred to herein as “perfumed products”), typically to impart a desired odour to the product itself or to a substrate following use of the product, eg on skin following use of a fine fragrance product, perfumed soap etc, on clothes following use of a perfumed laundry product etc. Perfumes are usually used by being formulated into mixtures of perfumes, often containing a large number of different perfumes, to produce a mixture having desired odour properties, typically mixed with or dissolved in a suitable solvent or mixed with a solid substrate.
It is known that certain perfumes are liable to suffer from reduced efficacy over time on storage in a perfumed product. This can be due to loss of volatile fragrant materials, such as volatile aldehydes and alcohols, or due to degradation, eg as a result of chemical reaction with other materials such as bleach in the product, with oxygen in ambient air etc. Some perfumes are also chemically unstable in use and so do not function to impart odour properties for as long as desirable: for example, aldehydes can be subject to oxidation on exposure to air.
In an attempt to overcome such problems, so-called “pro-perfumes” or “pro-fragrances” have been devised. These generally comprise a derivative of a perfume that is more stable than the perfume itself, eg being less volatile, being chemically protected from taking part in undesired reactions etc, and from which the perfume can be released in use, eg in response to water (hydrolysis), heat (thermolysis) etc. The pro-perfume is included in a mixture of perfumes or a perfumed product in place of the perfume. See, for example, WO 99/46318 which concerns various silicone polymer pro-fragrances.
WO 00/02981 discloses laundry and cleaning compositions including a product of reaction between a primary and/or secondary amine compound e.g. ethyl 4-aminobenzoate (having an Odour Intensity Index of less than that of a 1% solution of methylanthranilate in dipropylene glycol) and a perfume component selected from ketone, aldehyde and mixtures thereof, the reaction product generally being an azomethine (also known as a Schiff's base or imine). Delayed release of the perfume (ketone or aldehyde) from the reaction product is obtained, which is believed to occur by mechanisms including hydrolysis, photochemical cleavage, oxidative cleavage or enzymatic cleavage. The amine reaction product is preferably preformed before incorporation into the laundry and cleaning composition, to enable better control of the yield and purity of the reaction product and avoid possible interaction with perfume present in the composition. Where the laundry and cleaning compositions include perfume, the amine reaction product is preferably incorporated in the composition separately from the perfume, for better control of the amine reaction product and subsequent perfume release therefrom.
WO 00/02982 is generally similar to WO 00/02981, but requires the use of an amino functional polymer comprising at least one primary amine and/or secondary amine group.
It is also known to use various 4-aminobenzoate esters (i.e. para-aminobenzoate esters) in perfumed products because of the sunscreen properties of the esters. For example, U.S. Pat. No. 3,330,730 discloses aerosol sunscreen compositions including N,N-dimethyl isoamyl para-aminobenzoate or glyceryl para-aminobenzoate. DE 1492322 concerns the use of UV-absorbing substances as additives for cosmetics and discloses, e.g., use of monoglyceryl p-aminobenzoate in a toilet water.
EP 1004652 concerns use of various aminobenzoate derivatives, particularly methyl ortho-aminobenzoate (methyl anthranilate), as adjuvants for reducing adaptation to odour-emitting substances such as perfumes.
The present invention is based on an alternative approach to enhancing perfume efficacy, not using pro-perfumes or pro-fragrances, which aims to overcome the problems discussed above.